The present invention relates to dissolvable intraluminal stents for mammalian anastomoses.
Surgical anastomosis is the procedure of choice to relieve or correct blocked, diseased or otherwise inoperative luminal vessels. The most common vessel to which this procedure is applied is the intestine, but the procedure may also be used to correct abnormalities in blood vessels, biliary and urinary ducts, for example, as well as other vessels. However, it has been long recognized that there is a need for an essentially sutureless procedure.
As early as 1892, J. B. Murphy reported sutureless anastomosis procedures using what he called an anastomosis button. J. B. Murphy "Cholecysto-Intestinal, Gastro-Intestinal Entero-Intestinal Anastomosis, An Approximation Without Sutures," Medical Record, 42(24):665-76 (Dec. 10, 1892). The techniques described by Murphy were adopted by the medical community for several decades and the button became commonly called the "Murphy button." The Murphy button generally comprised a two-part metal clamping device which, when screwed together, would hold the two vessel stumps in close proximity until scar tissue joined the two stumps. However, one major disadvantage was that the button, when used in intestinal anastomosis procedures, would either pass several days after the surgical procedure, causing great discomfort, or would become lodged in the intestinal lumen, causing serious blockage. Blockage could also occur when feces packed the transit canal. In addition, necrosis at the anastomosis site was prevalent when using the Murphy button, sometimes resulting in infection and/or lumen obstruction due to stenosis.
More recently, a sophisticated variant of the Murphy button has been developed and is commonly called the bowel anastomosis ring (BAR). The early work of the BAR was performed and reported by T. G. Hardy et al., "A Biofragmentable Ring for Sutureless Bowel Anastomosis", Dis. Col. & Rect., 28:484-90 (1985), with later work by Hardy and others. T. G. Hardy et al., "Initial Clinical Experience With a Biofragmentable Ring for Sutureless Bowel Anastomosis," Dis. Col & Rect., 30:55-61 (1987); J. W. Maney et al., "Biofragmentable Bowel Anastomosis Ring: Comparative Efficacy Studies in Dogs," Surgery, 103(1):56-62 (1988); C. J. Cahill et al., "Sutureless Large Bowel Anastomosis: European Experience With the Biofragmentable Anastomosis Ring," Br. J. Surg., 76(4):344-47 (1989). The BAR functions similarly to the Murphy button by holding two vessel stumps in contact with one another after securing each of the vessel stumps to the BAR with a purse-string suture and snapping the two BAR pieces together.
The BAR is fashioned from a composition that fragments under normal intraluminal conditions and these BAR fragments are usually expelled about two to three weeks after implantation. However, these fragments are irregular, generally several millimeters to over 2 centimeters in length, thereby causing discomfort when passed. Other complications include the premature breaking away of the whole BAR from its site with the possibility of compromising the anastomosis and having to pass the intact device. The BAR cannot be installed above an intact ileocecal valve since the fragments could obstruct or tear the valve. Moreover, in the descending colon, the BAR may become obstructed by feces and cause signs of low bowel obstruction which usually pass when the BAR fragments, but this commonly prolongs the hospital stay of the patient. This problem is exacerbated when the BAR is situated lower in the descending colon and sigma where the feces are increasingly denser, resulting in a corresponding increased tendency to plug the canal for intestinal contents to transit through the BAR before it fragments.
In addition, the BAR anastomosis procedure requires that purse-string sutures be inserted and tied and must remain in the vessel stumps to attach these stumps to the BAR after the surgical procedure has been completed. These sutures may remain in the vessel tissue for several days to several weeks and their presence, in addition to the pressure of the BAR clamping the two stumps together, increases the risk of edema, ischemia, infection, necrosis and perforation. Moreover, despite efforts to decrease this necrosis at the anastomosis, primarily accomplished by providing the BAR with interdigitating parts which lock at various gap sizes, necrosis may still occur at the site of purse-string sutures following the BAR procedure. Since the selection of gap sizes is limited and the gap distances are relatively narrow, it is possible that the vessel stumps may be too thick to be inserted into the BAR before closing. Also, when the thickness of the stumps are nearly equal to the gap size, closing the BAR causes an increase in vascular damage, resulting in edema and consequent problems, such as ischemia, necrosis and micro- or macronecrosis and perforation and thus, causing minor or major leakage of intestinal or vessel contents into body cavities.
In addition, using conventional BAR and other suturing devices in hard to reach places, such as the low rectum or esophagus, it is particularly difficult to position the device for desired placement and clamping effects.
Still further, sucrose base stents which dissolve are particularly fragile, tending to break or fracture during anastomosis procedures, rendering them useless and in need of replacement to complete the surgical procedure.
The present invention overcomes the inefficiencies and deficiencies of the prior art by virtue of an improved anastomotic stent and placement device for anastomosis procedures which is believed to be more reliable in most uses, simplifies the surgical procedure, and may lessen the surgical complications and postoperative discomfort to the patient, in addition to shortening the hospital stay.